Ever since Pope Francis spoke compassionately about gay people last summer — saying, “Who am I to judge?” — Roman Catholics around the world have debated the meaning of his words.

That debate continued this week at Cardinal Spellman High School in the Bronx, where on Monday night the Catholic institution announced that an address by a recently retired priest from the New York Archdiocese about the issue of same-sex attraction, set for Tuesday, had been postponed.

The priest, the Rev. Donald G. Timone, has long been involved with the Courage organization, a spiritual support group formalized in New York in 1980 to encourage men and women with same-sex attractions to remain celibate. It is now based in Norwalk, Conn.

“The issue is one that tends to generate more heat than light,” and Father Timone “will be able to illuminate our thinking along truly Catholic lines,” an announcement listed on the school’s website had stated.

The school’s principal, the Rev. Trevor Nicholls, sent an email to reporters on Monday night announcing the postponement, “on the advisement of the board of trustees.”

Earlier, Joseph Zwilling, a spokesman for the archdiocese, said Father Nicholls told him last week that the invitation for Father Timone to speak had come from the school’s parents association. Mr. Zwilling said the archdiocese had no official position on the visit. Father Timone did not return a call on Monday.

In a statement, Father Nicholls had said that the talk would be for parents, not pupils. He urged against any premature judgments. “Parents are the first educators of their children,” he said, “and our aim is to provide them from time to time with the opportunity to listen to speakers who, in one area or another, may be able to offer them information, guidance and support as they fulfill that role.”

Before the postponement, however, several alumni expressed concern that the event would send an alienating message to young people, particularly those in the process of self-discovery or those with a gay relative. Some said they planned to attend the priest’s 7:30 p.m. talk, or possibly hold a candlelight vigil across the street as it took place.

An effort called, “Gay? Fine by Me,” took root on Facebook, and an online petition calling for the talk to be canceled, and for the conversation to be redirected toward one of “support and inclusion,” had more than 200 signatures by Monday afternoon.

“As a gay kid there, I was bullied of course, but I always felt like I could go to a faculty member to vent or talk or whatever,” Carlos Tomas Solano, 38, a speech pathologist from the school’s class of 1993, said in an interview.

“I feel like since this situation is coming from up above, from administration, I feel like these teachers are being put in a position where they cannot help a student struggling with their sexuality, and this is where my anger stems from.”

Another graduate, Gypsy Guillen Kaiser, an independent advocacy strategist, said in an interview: “The Catholic Church is never going to celebrate homosexuality, but it is another thing to saddle these children with guilt.”

On Monday, several students at the school said that they knew about the priest’s plans to visit only from social media, or friends, but not from teachers or school leaders. They said that Spellman students in general saw sexual orientation as a nonissue, and that no antigay teachings were part of the curriculum.

As she arrived for school, Aneesa Alli, 17, a senior, explained that in her religion class, “Theology of the Body,” her teachers noted that being gay was a type of sexuality and nothing more.

“They don’t make it a big deal because some of the kids in the class were gay,” she said. “They don’t try to make you uncomfortable.”

One student, Junelle Adei, 15, a sophomore, said that while she was “completely accepting of gay people,” it was important to take time to listen to Father Timone’s message. Another, Eddie Ellis, 14, a freshman, credited Pope Francis with helping to mold the school’s sexually tolerant attitude.

Several people involved in Courage said its aim was not to convert gay people to a heterosexual lifestyle, a so-called conversion therapy that has been banned in certain circumstances in New Jersey and in California.

“If any of the members, on their own, wanted to seek that, we would support people in that,” said the Rev. John F. Doerfler, the vicar of the diocese in Green Bay, Wis., where a Courage chapter began a few years ago. “But that is not our focus. That is not what we do.”

Pope Francis made headlines in July in diverging sharply from past Vatican messages, which had included equating homosexuality with evil. “If someone is gay, and he searches for the Lord, and has good will, who am I to judge?” the pope said.

To Francis DeBernardo, the executive director of New Ways Ministry, which works to connect the church with lesbian, gay, bisexual and transgender people, the planned appearance by Father Timone seemed to be going against a trend. He said several Catholic high schools and colleges had support programs for gay students and worked to help them form alliances with straight students.

“I have to imagine that this is going to present a very negative view of lesbian and gay people to young people,” Mr. DeBernardo said of the event planned for Tuesday in the Bronx. “It is going to create a lot of conflict in their lives, unneeded conflict.”

A version of this article appears in print on , Section A, Page 19 of the New York edition with the headline: A Talk That Stirred Fear of Antigay Bias Is Delayed. Order Reprints | Today’s Paper | Subscribe